How to sync two imap server?

I have online email account. At office I have 8 computer with Outlook client which are all connecteted with this account with imap protocol. I want to create my own local mail server which will be synchronized with my online mail account. All my office computers will retrive mails from my local mail server. Syncronization between online and local mail server must be bidirectional. If i delete anything on local, should be deleted online.

Thanks, A